is my job too dangerous to work until I deliver???

I'm 32 weeks on Thursday, my job is as a behavior technician at a mental health facility for children with autism& other behavioral disorders. Ages range from 4 years old to 16. 
We are trained to do specific holds/restraints allowed by state. I've been head butted in the chest, kicked, punched, bir, peed, and spit on. It wasn't a big deal to me when I wasn't pregnant, but my job still won't recognize that I would like to be away from the violent kids who kick/punch/bite because I am worried about my belly getting hit, or me falling. Yet today I had 6 big kids 13 & older by myself and got kicked, pushed,& bit twice. My belly was safe, but I had a headache& my belly ached from tending up from the anxiety it caused me for the rest of the day. 
I planned on working up until I go into labor but I don't think it's too unreasonable any more to use my vacation time to be off a week and a half before I'm due. I'm due the 15th of December & I wanted to be done at the end of November. How long before you're due are you guys stopping your jobs? Any suggestions?